Although infants use their memories to learn new information, few adults can remember events in their lives that happened prior to the age of three. Psychologists have now documented that age seven is when these earliest memories tend to fade into oblivion, a phenomenon known as “childhood amnesia.” The study is the first empirical demonstration of the onset of childhood amnesia, and involved interviewing children about past events in their lives.

An interesting study tracking when children began to forget their earliest memories. I found this passage especially interesting:

Young children tend to forget events more rapidly than adults do because they lack the strong neural processes required to bring together all the pieces of information that go into a complex autobiographical memory, she explains. “You have to learn to use a calendar and understand the days of the week and the seasons. You need to encode information about the physical location of the event. And you need development of a sense of self, an understanding that your perspective is different from that of someone else.”

My take on this is that long term memory requires an information structure that we can use to file memories into. Before we understand the concept of a year or school roles, the memories are just jumbled impressions that we can probably only recall haphazardly, at best. Once we are able to categorize memories into years and months, into understood location and modes, it probably becomes easier to keep them long term.

Of course, as I’ve speculated before, I think that we tend to retain memories that we recall. Un-recalled memories fade, and we don’t even realize that they’re gone. Recalled memories, of course, get copied and re-stored, and hence modified, so they degrade in accuracy over time.

This is particularly true when you remember that memories are slotted within a structure. That structure isn’t a static thing. It changes over time. And that almost certainly changes the memories.

I still remember my shock at how small my childhood home was, when I saw it decades later as an adult. I didn’t recall it being that small, probably because I had re-stored those memories within my later modified framework of what a house was, which was larger than that early childhood version.